The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform

G Rolland - One of the best experts on this subject based on the ideXlab platform.

  • taylor couette poiseuille flow and heat transfer in an Annular Channel with a slotted rotor
    International Journal of Thermal Sciences, 2017
    Co-Authors: Nicolas Lancial, Federico Torriano, F Beaubert, Souad Harmand, G Rolland
    Abstract:

    Abstract This paper investigates a Taylor-Couette-Poiseuille flow in an Annular Channel of a slotted rotating inner cylinder, corresponding to a salient pole hydrogenerator. The purpose of this study is to improve the understanding of flow and thermal phenomena in electrical machines using a simplified scale model. The validation of the numerical model for a specific configuration is first shown by comparing the results with the experimental data. A parametric study is also performed to investigate all main flow regimes and to derive correlations in terms of the Nusselt number distribution on the rotor pole face and sides. The results show that the Nusselt number is proportional to the tangential Reynolds number to the power 1/7 in the pole and inductive faces trailing side. This relationship is similar to the one encountered in classical Taylor-Couette-Poiseuille flows between two concentric and smooth cylinders.

  • study of a taylor couette poiseuille flow in an Annular Channel with a slotted rotor
    International Conference on Electrical Machines, 2014
    Co-Authors: Nicolas Lancial, Federico Torriano, F Beaubert, Souad Harmand, G Rolland
    Abstract:

    This paper investigates a Taylor-Couette-Poiseuille flow in an Annular Channel of a slotted rotating inner cylinder, corresponding to a salient pole hydrogenerator. The purpose of this study is to improve the understanding of flow and thermal phenomena in electrical machines using a simplified scale model. Some numerical tests are first shown to investigate the influence of certain numerical parameters. Finally, CFD and CHT studies of the flow regimes are presented in the slotted rotor geometry and compared to experimental and literature data.

Nicolas Lancial - One of the best experts on this subject based on the ideXlab platform.

  • taylor couette poiseuille flow and heat transfer in an Annular Channel with a slotted rotor
    International Journal of Thermal Sciences, 2017
    Co-Authors: Nicolas Lancial, Federico Torriano, F Beaubert, Souad Harmand, G Rolland
    Abstract:

    Abstract This paper investigates a Taylor-Couette-Poiseuille flow in an Annular Channel of a slotted rotating inner cylinder, corresponding to a salient pole hydrogenerator. The purpose of this study is to improve the understanding of flow and thermal phenomena in electrical machines using a simplified scale model. The validation of the numerical model for a specific configuration is first shown by comparing the results with the experimental data. A parametric study is also performed to investigate all main flow regimes and to derive correlations in terms of the Nusselt number distribution on the rotor pole face and sides. The results show that the Nusselt number is proportional to the tangential Reynolds number to the power 1/7 in the pole and inductive faces trailing side. This relationship is similar to the one encountered in classical Taylor-Couette-Poiseuille flows between two concentric and smooth cylinders.

  • study of a taylor couette poiseuille flow in an Annular Channel with a slotted rotor
    International Conference on Electrical Machines, 2014
    Co-Authors: Nicolas Lancial, Federico Torriano, F Beaubert, Souad Harmand, G Rolland
    Abstract:

    This paper investigates a Taylor-Couette-Poiseuille flow in an Annular Channel of a slotted rotating inner cylinder, corresponding to a salient pole hydrogenerator. The purpose of this study is to improve the understanding of flow and thermal phenomena in electrical machines using a simplified scale model. Some numerical tests are first shown to investigate the influence of certain numerical parameters. Finally, CFD and CHT studies of the flow regimes are presented in the slotted rotor geometry and compared to experimental and literature data.

E. A. Boltenko - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of Heat Transfer and Pressure Drop in an Annular Channel with Heat Transfer Intensifiers
    Thermal Engineering, 2015
    Co-Authors: E. A. Boltenko, A. N. Varava, A. V. Dedov, A V Zakharenkov, A. T. Komov, S. A. Malakhovskii
    Abstract:

    Results from systematic investigations of heat transfer and pressure drop for water flow in an Annular Channel using an efficient method for enhancing heat transfer on a convex heating surface are presented. The main technical data of the thermal-hydraulic experimental setup are given together with a brief description of the control, monitoring, and physical parameters measurement and recording systems, as well as primary experimental data processing and storage system. The test section, the enhancement method based on setting up swirl flows, the geometrical characteristics of intensifiers, their schematic design, and installation technology are described. The experimental data are obtained in a wide range of coolant flow parameters under the conditions of single-phase convection with using intensifiers having different shapes. The test measurements carried out on a smooth Annular Channel showed good agreement with the classic correlations both for heat transfer and pressure drop, thereby confirming reliability of the experimental data. A considerable improvement in heat removal efficiency on the convex heating surface is obtained. The value of heat transfer coefficient is a factor of 1.8 higher than it is for smooth Annular Channels. The region of the values of intensifier geometrical characteristics and Reynolds numbers for which the growth of heat transfer prevails over the growth of pressure drop is established. It is shown that the maximums of heat transfer and pressure drop are observed at quite definite values of intensifier geometrical characteristics. The primary experimental data are processed and presented as a dependence of the Nusselt number on the Reynolds number for different values of the intensifier’s relative fin height Ḣ. The value of Ḣ at which heat transfer reaches its maximum is found. The experiments were carried out in the pressure range p = 3.0–10.0 MPa and at the constant temperature of liquid at the test section inlet equal to 100°C. The influence of peripheral liquid flow swirling pitch on heat transfer and pressure drop is studied. An empirical correlation describing the dependence of heat transfer on the intensifier geometrical characteristics is obtained.

  • Study of heat transfer on concave and convex surfaces of an Annular Channel with flow swirling
    Thermal Engineering, 2006
    Co-Authors: E. A. Boltenko
    Abstract:

    Results of experimental studies of postcrisis heat transfer in Annular steam-generating Channels are presented. It is recognized that, in Annular Channels with flow swirling, the value of the vapor quality at which deteriorated postcrisis heat transfer takes place and the intensity of heat transfer on convex and concave surfaces are different. Correlations for determination of heat transfer coefficients on these surfaces in the Annular Channel with flow swirling are presented.

Hwanyeol Kim - One of the best experts on this subject based on the ideXlab platform.

  • convective heat transfer to co2 at a supercritical pressure flowing vertically upward in tubes and an Annular Channel
    Experimental Thermal and Fluid Science, 2009
    Co-Authors: Yoonyeong Bae, Hwanyeol Kim
    Abstract:

    The Super-Critical Water-Cooled Reactor (SCWR) has been chosen by the Generation IV International Forum as one of the candidates for the next generation nuclear reactors. Heat transfer to water from a fuel assembly may deteriorate at certain supercritical pressure flow conditions and its estimation at degraded conditions as well as in normal conditions is very important to the design of a safe and reliable reactor core. Extensive experiments on a heat transfer to a vertically upward flowing CO{sub 2} at a supercritical pressure in tubes and an Annular Channel have been performed. The geometries of the test sections include tubes of an internal diameter (ID) of 4.4 and 9.0 mm and an Annular Channel (8 x 10 mm). The heat transfer coefficient (HTC) and Nusselt numbers were derived from the inner wall temperature converted by using the outer wall temperature measured by adhesive K-type thermocouples and a direct (tube) or indirect (Annular Channel) electric heating power. From the test results, a correlation, which covers both a deteriorated and a normal heat transfer regime, was developed. The developed correlation takes different forms in each interval divided by the value of parameter Bu. The parameter Bu (referred to as Bu hereafter), amore » function of the Grashof number, the Reynolds number and the Prandtl number, was introduced since it is known to be a controlling factor for the occurrence of a heat transfer deterioration due to a buoyancy effect. The developed correlation predicted the HTCs for water and HCFC-22 fairly well. (author)« less

Manop Pipathattakul - One of the best experts on this subject based on the ideXlab platform.

  • effects of the gap size on the flow pattern maps in a mini gap Annular Channel
    Experimental Thermal and Fluid Science, 2014
    Co-Authors: Manop Pipathattakul, Omid Mahian, Ahmet Selim Dalkilic, Somchai Wongwises
    Abstract:

    Abstract An experimental study has been performed to examine the effects of gap size on the flow pattern maps of air–water two-phase flow inside a mini-gap Annular Channel with inclination angles (θ) of 0°, 30°, and 60°. The tests are conducted for three different sizes of the inner diameters (Di) of the concentric Annular test section—namely 8, 10, and 11 mm—while the outer diameter is equal to 12.5 mm. The flow pattern maps are presented for various types of flow including plug flow, slug flow, Annular/slug flow, Annular flow, bubbly/plug flow, bubbly/slug–plug flow, churn flow, and dispersed bubbly flow, regarding the alteration of gap sizes and inclination angles. According to the experimental conclusions, the angle of inclination and the various gap sizes are influential in the transition of flow regimes.

  • flow pattern pressure drop and void fraction of two phase gas liquid flow in an inclined narrow Annular Channel
    Experimental Thermal and Fluid Science, 2006
    Co-Authors: Somchai Wongwises, Manop Pipathattakul
    Abstract:

    Two-phase flow pattern, pressure drop and void fraction in horizontal and inclined upward air-water two-phase flow in a mini-gap Annular Channel are experimentally studied. A concentric Annular test section at the length of 880mm with an outer diameter of 12.5mm and inner diameter of 8mm is used in the experiments. The flow phenomena, which are plug flow, slug flow, Annular flow, Annular/slug flow, bubbly/plug flow, bubbly/slug-plug flow, churn flow, dispersed bubbly flow and slug/bubbly flow, are observed and recorded by high-speed camera. A slug flow pattern is found only in the horizontal Channel while slug/bubbly flow patterns are observed only in inclined Channels. When the inclination angle is increased, the onset of transition from the plug flow region to the slug flow region (for the horizontal Channel) and from the plug flow region to slug/bubbly flow region (for inclined Channels) shift to a lower value of superficial air velocity. Small shifts are found for the transition line between the dispersed bubbly flow and the bubbly/plug flow, the bubbly/plug flow and the bubbly/slug-plug flow, and the bubbly/plug flow and the plug flow. The rest of the transition lines shift to a higher value of superficial air velocity. Considering the effect ofmore » flow pattern on the pressure drop in the horizontal tube at low liquid velocity, the occurrence of slug flow stops the rise of pressure drop for a short while, before rising again after the air velocity has increased. However, the pressure does not rise abruptly in the tubes with {theta}=30{sup o} and 60{sup o} when the slug/bubbly flow occurs. At low gas and liquid velocity, the pressure drop increases, when the inclination angles changes from horizontal to 30{sup o} and 60{sup o}. Void fraction increases with increasing gas velocity and decreases with increasing liquid velocity. After increasing the inclination angle from horizontal to {theta}=30{sup o} and 60{sup o}, the void fraction appears to be similar, with a decreasing trend when the inclination angle increases. (author)« less